JP6106523B2 - Method for producing polyurethane foam for cosmetic application - Google Patents

Description

  The present invention relates to a method for producing a polyurethane foam for cosmetic application and a polyurethane foam for cosmetic application used in a sponge puff for applying cosmetics such as powdery foundation and liquid foundation, or an application part of an eye chip.

  Conventionally, the following materials are known as materials for foam for cosmetic application.

[Wet polyurethane]
As an applicator made of wet polyurethane foam, for example, one disclosed in Patent Document 1 is known. Wet polyurethane foam dissolves a polyurethane polymer in dimethylformamide, stirs a composition containing a pore-forming agent such as polyvinyl alcohol, fills it into a predetermined mold and gels, then generates pores with a large amount of water. It is manufactured by eluting the agent. The cell structure of the wet polyurethane foam produced by this method has a structure like a cocoon (hereinafter referred to as a cocoon-like structure) due to aggregation of the resin. It is known that the wet polyurethane foam having such a cell structure has a smooth feel and a good feel. However, since dimethylformamide has a high environmental impact, it is designated as a first-class designated chemical substance by the Chemical Substance Emission Grasping Management Promotion Act (PRTR Law) and is difficult to use in large quantities. In addition, the above method is costly in terms of process and material. In addition, since the above wet polyurethane foam has a cell-like structure, when a liquid foundation is used, most of the foundation enters the foam and is not used for coating, but the amount of the foundation taken into the foam There is a problem that increases.

[Dry polyurethane]
A general dry polyurethane foam uses a polyol having a functional group number larger than bifunctional, and is foamed using water as a blowing agent and a low-boiling compound such as chlorofluorocarbon, dichloromethane or hydrocarbon as an auxiliary blowing agent. In general, the dry polyurethane foam produced by this method becomes rough with an average cell diameter of 300 μm or more. Moreover, when water is used as the foaming agent, the urea bond formed by the reaction of water and isocyanate functions as a hard segment in the resin skeleton. For this reason, the dry polyurethane foam is rough and unpleasant to the touch.

  Carbon dioxide gas generated by water foaming has high resin permeability. For this reason, since the speed at which carbon dioxide gas escapes to the outside through the cell membrane of the foam is faster than the speed at which air flows from the outside of the foam, the pressure in the cell tends to be low. And when the cell diameter is made small for the purpose of improving the feel and the foam is made flexible, or when the closed cell ratio is raised for the purpose of reducing the penetration of the liquid foundation into the foam, There is a problem that the strength cannot resist the pressure drop in the cell and the foam shrinks, the curing reaction proceeds in the state as it is, and it cannot be restored in the contracted state.

  When foaming is carried out using only the auxiliary foaming agent without using water as the foaming agent, auxiliary foaming agents such as chlorofluorocarbon and dichloromethane are not suitable because of the high environmental load, and are not suitable for hydrocarbon-based (cyclopentane, etc.) Auxiliary foaming agents are flammable and require a large investment in safety measures for manufacturing equipment. In addition, the foam foamed using only the auxiliary foaming agent has many closed cells, and when the resin skeleton is softened, the liquefaction of the auxiliary foaming agent begins when the temperature drops after the foam is heated by reaction heat. Then, the pressure inside the cell decreases and contraction occurs. When the curing reaction proceeds in this state, a phenomenon that the original state does not return in a contracted state occurs.

  For example, Patent Document 2 discloses an example of a method for manufacturing a dry type cosmetic tool. This technique specifies the use of water as a blowing agent. In this method, since water is mainly used as a foaming agent, carbon dioxide gas is generated and urea bonds are formed in the molecular skeleton. Since the urea bond functions as a hard segment in the skeleton, the foam tends to be rough and tends to be inferior in touch. When trying to improve the texture by reducing water, the foaming ratio is reduced, the density is increased, and the whole becomes hard.

  Patent Document 3 discloses a method for producing a water-absorbing polyurethane foam having an isocyanate index in the range of 35 to 50 and water in a range of 1.0 to 3.0 parts by mass with respect to 100 parts by mass of polyol. Yes. In this method, water does not function as a foaming agent, but functions as a raw material for foam breaking for making cells communicate. This method can improve the water absorption and water retention of the polyurethane foam, but is insufficient to give the soft and smooth texture required for a cosmetic sponge puff. In addition, since the opening in the cell becomes large by making it communicate, the amount of liquid foundation that penetrates into the foam increases when applying liquid foundation, and the amount of liquid foundation that can actually be used for makeup is small There is a problem of becoming.

[NBR latex]
Cosmetic application sponges made of NBR latex foam are commercially available. The NBR latex foam has a cell structure with a large opening due to manufacturing problems, and the liquid foundation easily penetrates into the sponge, and there is a problem that the amount of liquid foundation that can actually be used is reduced. In addition, the tactile sensation can be improved to some extent by adjusting the materials and cells, but it is difficult to have a smooth texture like wet polyurethane.

[Silicone foam]
A sponge for applying a liquid foundation made of silicone foam is also commercially available. Silicone foam has a closed-cell structure, so when applying a powdery foundation, the particles that make up the foundation accumulate on the surface of the foam and crush the surface of the foundation when rubbing the surface of the foundation with the foam. It causes a phenomenon called caking that cannot be removed.

Japanese Patent Publication No. 58-189242 JP 2001-354741 A Japanese Patent No. 3402864

  An object of the present invention is to provide a polyurethane foam for cosmetic application at a low cost, which does not soak liquid foundation, does not cause powdery foundation caking, has a good feeling of use, and has a low environmental impact.

  The method for producing a polyurethane foam for cosmetic application according to the present invention comprises producing a polyurethane foam by mechanical foaming using a polyol, a polyisocyanate, a catalyst, a foam stabilizer and an inert gas. Using a bifunctional polyol having a classification rate of 70% or more and a number average molecular weight of 1000 to 3000 in an amount of 30% by mass or more, and having an average primary conversion rate of terminal hydroxyl groups of all polyols of 50% or more, Using a polyisocyanate in the range of an isocyanate index of 85 to 130, the amount of the inert gas supplied in terms of volume at 0 ° C. and 1 atm, and the total amount of liquid raw materials containing the polyol, polyisocyanate, catalyst and foam stabilizer It is characterized by being 2 to 10 times the supply amount.

The polyurethane foam for cosmetic application according to the present invention has a density of 60 kg / m ³ to 300 kg / m ³ , an Asker F hardness of 30 ° to 70 °, a ventilation resistance of 2 kPa · sec / m to 250 kPa · sec / m, and a tensile strength. Is 50 kPa or more.

  The polyurethane foam for cosmetic application according to the present invention can be produced, for example, by the above production method.

  According to the present invention, it is possible to provide a low-cost polyurethane foam for cosmetic application that has less penetration of the liquid foundation, does not cause powdery foundation caking, has a good feeling of use, and has a low environmental impact.

The photograph which image | photographed the sponge puff for makeup | decoration of Example 9 with 100-times multiplication factor with the scanning electron microscope. The photograph which image | photographed the cosmetic sponge puff of Example 10 with the magnification of 100 time with the scanning electron microscope. The photograph which image | photographed the cosmetic sponge puff of the comparative example 10 with the scanning electron microscope at 100 time magnification. The photograph which image | photographed the cosmetic sponge puff of the comparative example 11 with the magnification of 100 time with the scanning electron microscope.

  Embodiments of the present invention will be described below.

  The present inventors have found that it is preferable to produce a highly flexible foam with as little foaming agent as possible in order to solve the problems of conventional foam for cosmetic application.

  In the present invention, mechanical foaming is used in which an inert gas is forcibly introduced into the polyurethane raw material while mixing and stirring. Examples of the inert gas include noble gases such as helium, neon, and argon, nitrogen gas, and dry air. From the viewpoint of cost, it is preferable to use nitrogen gas or dry air.

  The mechanical foaming device may be used for continuous foaming or batch foaming. Examples of the mechanical foaming apparatus for continuous foaming include a disk-type mixer such as an Oaks mixer and a cylindrical mixer manufactured by Mondomix. An example of a mechanical foaming apparatus for batch foaming is a desktop whipper. In consideration of mass productivity, a continuous foaming device is preferable in which the cells are uniform and pinholes are unlikely to occur.

  The addition amount of the inert gas at the time of mechanical foaming is 2 to 10 times, more preferably 3 to 5 times the total supply amount of polyurethane raw material in terms of volume at 0 ° C. and 1 atm.

  When the addition amount of the inert gas is low, the density of the polyurethane foam increases and the texture becomes hard. If the amount of the inert gas added to the polyurethane raw material is too large, it is discharged as a gas pool, causing voids and pinholes. This tendency appears when the addition amount of the inert gas exceeds 10 times the total supply amount of the polyurethane raw material.

  Among the polyurethane raw materials in the present invention, the polyol contains 30% by mass or more, preferably 50% by mass or more, of a bifunctional polyol having a terminal hydroxyl group primary ratio of 70% or more and a number average molecular weight of 1000 to 3000. . As the polyol, only a bifunctional polyol (100% by mass) having a terminal hydroxyl group primary ratio of 70% or more and a number average molecular weight of 1000 to 3000 may be used. When a mixture of a bifunctional polyol having a terminal hydroxyl group primary ratio of 70% or more and a number average molecular weight of 1000 to 3000 and another polyol is used, the average number of functional groups of all polyols is 1.8 to 3.5. It is preferable that

  A general dry polyurethane foam is obtained by using a polyol having a functional group number larger than bifunctional and foaming using water as a blowing agent and a low-boiling compound such as chlorofluorocarbon, dichloromethane or hydrocarbon as an auxiliary blowing agent. Polyurethane foam is not strong enough as a sponge puff for cosmetic application, and pinholes are generated, resulting in poor appearance and feeling of use. In addition, when the number of functional groups of the polyol increases, the tensile strength of the polyurethane foam decreases, and tearing tends to occur when used.

  In the present invention, the above problem is solved by using a bifunctional polyol in an amount of 30% by mass or more of the total polyol. When the bifunctional polyol is less than 30% by mass of the total polyol, a low-density foam containing fine cells cannot be obtained, the density of the foam increases, the hardness increases, and the tactile sensation deteriorates.

  In mechanical foaming, the type of polyol greatly contributes to the foaming ratio of the polyurethane foam. Specifically, polyol reactivity, viscosity, and affinity with polyisocyanate affect the foaming ratio of polyurethane foam. Since the addition polymer containing only propylene oxide and not containing ethylene oxide has low reactivity, the stability of the polyurethane foam cell is low, and it is impossible to realize low density and softening. In order to stabilize the cell shape and reduce the density and soften it, it is preferable to increase the primary hydroxyl group conversion rate to about 70% or more with a bifunctional raw material, and to carry out addition polymerization of ethylene oxide at the polyol terminal Is effective.

  For example, in the presence of an acidic catalyst (addition polymerization catalyst), propylene oxide is addition-polymerized to an initiator to prepare a bifunctional polypropylene glycol having a terminal hydroxyl group primary conversion rate of 40% or more. A bifunctional polyol having a terminal hydroxyl group primary ratio of 70% or more and a number average molecular weight of 1000 to 3000 is prepared, and the bifunctional polyol is contained in an amount of 30% by mass or more. A polyol having a primary rate of 50% or more is prepared.

  By increasing the primary ratio of the terminal hydroxyl group of the polyol, the reactivity is increased and the cells can be maintained, so that the density of the foam can be reduced. If ethylene oxide is added to the initiator, the primary hydroxylation rate of the terminal hydroxyl group can be increased. However, the ethylene oxide adduct has high hydrophilicity and is easily swelled and broken when an aqueous foundation is used. In order to improve the water resistance, it is preferable to reduce the ratio of the ethylene oxide adduct in the molecule as much as possible.

  Generally, when propylene oxide is subjected to addition polymerization, the polymerization is carried out using an alkali catalyst. In this case, most of the propylene oxide is cleaved to become a secondary hydroxyl group, and the primary hydroxyl group is about 2%. In order to increase the primary ratio of the terminal hydroxyl group, it is preferable to add-polymerize propylene oxide and then add-polymerize ethylene oxide. It is difficult to ensure the primary ratio of terminal hydroxyl groups and to suppress the addition ratio of ethylene oxide.

  On the other hand, as disclosed in JP-A No. 2000-344881, as an example in the present invention, propylene oxide is addition-polymerized to an initiator in the presence of an acidic catalyst such as trispentafluorophenylborane, Polyurethane is produced by producing a product having a higher terminal hydroxyl group primary conversion rate, and further using an polyol by addition polymerization of ethylene oxide so that the terminal hydroxyl group primary conversion rate is 70% or higher, preferably 90% or higher. The water resistance of the foam can be improved.

  In the present invention, less than 1.0 part by weight of water may be used as a blowing agent with respect to 100 parts by weight of polyol. If water is used as an auxiliary foaming agent during mechanical foaming, the tactile sensation can be softened because the density can be reduced. As described above, in the case of water foaming, there is a possibility that the texture becomes rough and shrinks, but the shrinkage can be suppressed by suppressing the water to less than 1.0 part by mass, and further 0.7 mass. Roughness can be further reduced by setting it to less than or equal to part.

  Further, the present invention does not limit the foaming by adding chlorofluorocarbons, dichloromethane, or a hydrocarbon-based auxiliary foaming agent.

  In the present invention, the foam after foaming may be crushed. In the case of a sponge puff for makeup application made of a material having a high closed cell property, caking may occur when applying a powdery foundation. On the other hand, since the cells can be connected by crushing the foamed polyurethane foam, caking can be prevented and dimensional stability can be ensured. Moreover, by adjusting the crushing, the air permeability and hardness can be controlled, and an optimum material for a sponge puff for cosmetic application can be produced.

The polyurethane foam for cosmetic application according to the present invention has a density of 60 kg / m ³ to 300 kg / m ³ , an Asker F hardness of 30 ° to 70 °, a ventilation resistance of 2 kPa · sec / m to 250 kPa · sec / m, and a tensile strength. Is 50 kPa or more. Such a polyurethane foam for cosmetic application can be produced using the method of the present invention.

The density of the polyurethane foam is measured according to JIS K7222. When the density of the polyurethane foam is less than 60 kg / m ³ , the touch becomes rough and the feeling of use becomes worse, the cells become rough, or the resin strength is not maintained and the resin foam is broken. When the density exceeds 300 kg / m ³ , the polyurethane foam becomes hard and inflexible, and since it does not bend when taking the powder foundation, the foundation can be taken only in a linear form. By setting the density of the polyurethane foam to 60 to 300 kg / m ³ , these problems can be solved. The polyurethane foam preferably has a density of 70 to 200 kg / m ³ in order to achieve both a soft feel and a tensile strength that does not break during use.

  The hardness of the polyurethane foam is measured with an Asker F hardness tester. Specifically, a sample cut to a thickness of 8 mm is placed on an acrylic plate, and the hardness after 10 seconds is read by placing an Asker F hardness meter. If the polyurethane foam has an Asker F hardness of less than 30 °, it will cause a feeling of bottoming when the foundation is applied, and it will push in the shape of a finger. become. When the Asker F hardness exceeds 70 °, the polyurethane foam does not follow the skin, so that uniform application of the foundation becomes difficult. The polyurethane foam preferably has an Asker F hardness of 40 ° to 60 ° in order to achieve both a soft feeling and a restoring feeling.

  The ventilation resistance of the polyurethane foam is measured using KES-F8-AP1 manufactured by Kato Tech Co., Ltd. Specifically, a sample cut to a thickness of 8 mm is prepared, and a pressure measured by a semiconductor differential pressure gauge when a constant flow rate air is sent to the sample by a plunger / cylinder piston movement and is released into the atmosphere through the sample. Loss is evaluated as ventilation resistance. When the foam resistance of the polyurethane foam is less than 2 kPa · sec / m, the liquid foundation is easily penetrated. When the foam resistance of the polyurethane foam exceeds 250 kPa · sec / m, caking tends to occur when the powdery foundation is applied. When the airflow resistance of the polyurethane foam is 2 kPa · sec / m to 250 kPa · sec / m, the amount of liquid foundation penetrated can be reduced, and caking can be prevented from occurring when applying the powdery foundation.

  The tensile strength of the polyurethane foam is measured according to JIS K6400-5. When the polyurethane foam has a tensile strength of less than 50 kPa, the possibility of tearing during use increases. The tensile strength of the polyurethane foam is more preferably 70 kPa or more.

  The polyurethane foam is manufactured by adjusting the raw material formulation so that the density, Asker F hardness, ventilation resistance, and tensile strength in the above ranges are obtained.

As described above, by specifying the polyol raw material and further adjusting the equipment and manufacturing conditions, the density is 60 kg / m ^{3 to} 300 kg / m ³ , the Asker F hardness is 30 ° to 70 °, and the airflow resistance is 2 kPa · sec. / M to 250 kPa · sec / m, and a polyurethane foam having a tensile strength of 50 kPa or more can be produced.

  By making the cell finer, it is possible to improve the touch when used in a cosmetic puff application. The cell diameter can be measured according to JIS K6400-1, and the preferred cell diameter is 250 μm or less.

  Since such polyurethane foam has fine cells and is not completely open-celled like ordinary dry polyurethane foam, it can greatly reduce the penetration of the foundation into the foam when applying liquid foundation. it can.

  There is a correlation between the cell structure of the foam, the ventilation resistance and the penetration of the liquid foundation. Wet polyurethane foam and NBR latex foam have a ventilation resistance of less than 2 kPa · sec / m, and the liquid foundation easily penetrates. On the other hand, if the ventilation resistance exceeds 250 kPa · sec / m, caking is likely to occur when applying the powdery foundation. On the other hand, the polyurethane foam of the present invention produced by mechanical foaming has a ventilation resistance of 2 kPa · sec / m to 250 kPa · sec / m, and can reduce the amount of liquid foundation that penetrates.

  Further details will be described.

  In the present invention, a polyol and an isocyanate are used as main components, and a foam stabilizer and a catalyst are used as auxiliary agents. In some cases, a foaming agent, a crosslinking agent, an ultraviolet absorber, a light stabilizer, a pigment, an antioxidant, and an antibacterial agent. Etc. are added.

  As the polyol, a bifunctional polyol having a terminal hydroxyl group primary ratio of 70% or more and a number average molecular weight of 1000 to 3000 is used alone, or the bifunctional polyol is 30% by mass or more of the total polyol, preferably 50 It mixes with other polyol so that it may become a content rate more than% mass. As other polyols, polyether polyols, polyester polyols, polymer polyols and the like used in the production of polyurethane foams can be used alone or in combination. Even when the bifunctional polyol and another polyol are mixed, if the average primary ratio of terminal hydroxyl groups of all polyols is 50% or more, the foamability and foam stability necessary for mechanical foaming can be obtained. .

  Polyisocyanates include aromatic diisocyanates such as tolylene diisocyanate (TDI) and diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), norbornene diisocyanate (NBDI) used in the production of polyurethane foam. Aliphatic isocyanates such as hydrogenated diphenylmethane diisocyanate (MDI) and hydrogenated xylylene diphenylmethane diisocyanate (XDI) can be used alone or in combination.

  In general, MDI and TDI are used, but aliphatic isocyanates can also be used for the purpose of preventing yellowing by ultraviolet rays.

  When manufacturing by mechanical foaming, high viscosity is preferable to ensure the stability of the generated foam, and it is possible to prevent the cells from becoming large due to coalescence of the foam by accelerating the resinification reaction. Therefore, MDI-based raw materials are preferable.

  In the MDI-based raw material, if the amount of polymeric MDI is increased, the number of functional groups is increased, and the extensibility is deteriorated. Therefore, it is preferable to use monomeric MDI. Since pure monomeric MDI is a solid at room temperature, it is used after being heated to a liquid. It can also be made liquid at room temperature with the properties of monomeric MDI by partially reacting with a polyol for prepolymerization or carbodiimide modification. The latter is preferable because it can be manufactured with a simple apparatus.

  As the foam stabilizer, for example, a silicone foam stabilizer for polyurethane foams in which a polyether bond is combined with a polysiloxane bond can be used. In particular, a silicone-based foam stabilizer sold for mechanical foaming can be suitably used.

  As the catalyst, for example, a tin-based or bismuth-based metal catalyst or a tertiary amine catalyst can be used alone or in combination. A temperature-sensitive catalyst may be used to prevent curing from starting during stirring.

  An inert gas is used as the foaming gas and is forcibly mixed with the liquid raw material during mechanical foaming. As the inert gas, a rare gas (such as helium, neon, or argon), nitrogen gas, or dry air can be used. Considering the cost, it is preferable to use nitrogen gas or dry air.

  A blowing agent is used as an auxiliary. As the foaming agent, it is preferable to use a small amount of water that reacts with polyisocyanate to generate carbon dioxide. The blending ratio of water as the blowing agent is preferably less than 1.0 part by mass with respect to 100 parts by mass of the polyol.

  As the foaming agent, dichloromethane, various fluorocarbon raw materials, cyclopentane, methyl formate, liquefied carbon dioxide gas, etc., which are used for ordinary polyurethane foaming, may be used.

  As the crosslinking agent, for example, low molecular weight polyols such as 1,4-butanediol, trimethylolpropane, ethylene glycol, diethylene glycol and the like, and polyamines such as methylenebisdiphenylpolyamine, tolylenediamine and the like can be used.

  As the ultraviolet absorber, for example, titanium dioxide, zinc oxide, benzotriazole-based materials, benzophenone-based materials and the like can be used alone or in combination.

  As the light stabilizer, for example, a hindered amine-based material can be used.

  As the pigment, for example, a pigment dispersed in a polyol raw material may be used, or a dye may be used.

  As the antioxidant, for example, a hindered phenol raw material, a phosphite ester raw material and the like can be used.

  As the antibacterial agent, known ones such as those in which silver is supported on zeolite, an aqueous solution containing silver ions, an inorganic antibacterial agent or an organic antibacterial agent (such as zinc pyrithione or thiabendazole) can be used.

  The above raw materials are stirred by mechanical foaming while forcibly mixing an inert gas to start polyurethane reaction while forming cells.

  The polyurethane reaction liquid discharged from the foaming apparatus is slab-molded, and after the cured polyurethane foam is cut into a predetermined shape, the end portion is polished into an R shape to obtain a cosmetic sponge puff.

  The polyurethane reaction liquid discharged from the foaming apparatus can be introduced into a mold and molded.

  The cross-sectional shape of the mold is a cross-sectional shape that is slightly larger than the shape of the predetermined cosmetic puff.

  The foamed molded product thus obtained can be used as a cosmetic sponge puff by polishing its rear end into an R shape.

  A rod-like foam can also be produced by introducing a polyurethane reaction liquid into a cylindrical mold whose cross-sectional shape is one size larger than the shape of a predetermined decorative puff.

  The rod-like product thus obtained can be cut into a predetermined thickness, and its rear end portion can be polished into an R shape to form a cosmetic sponge puff.

  After uniformly applying the polyurethane reaction stock solution on the release sheet, the release sheet can be further placed on the upper surface to produce a sheet-like foam having a constant thickness.

  The sheet-like molded product thus obtained can be made into a cosmetic sponge puff by punching into a predetermined shape and then polishing the end into an R shape.

Examples 1-3 and Comparative Examples 1-5
Polyurethane foam for cosmetic application is manufactured by mechanical foaming using a raw material containing various polyols, using a disk-type Oaks mixer. Ease of entrainment of inert gas, that is, finer cell diameter and lower density of foam Then, the fragility of the foam was examined, and a polyol suitable for a polyurethane foam for cosmetic application was examined.

Example 1
In the presence of an acidic catalyst (addition polymerization catalyst), propylene oxide is addition-polymerized to an initiator having two functional groups to prepare a bifunctional polypropylene glycol having a terminal hydroxyl group primary conversion rate of about 70%, and further ethylene. Oxide was added to prepare a bifunctional polyol (polyol A) having a terminal hydroxyl group primary conversion of 92% and a number average molecular weight of 1400.

A polyol, a crosslinking agent, a foam stabilizer, an amine catalyst (urethane reaction catalyst), and a polyisocyanate were prepared so as to have the composition shown in Table 1. All of these raw materials are liquid. Water as a blowing agent is not used.

  A mixture of raw materials other than polyisocyanate is continuously supplied to Oaks mixer, nitrogen gas is supplied, discharged while reacting with polyisocyanate in Oaks mixer, and cured at 100 ° C for 7 minutes for cosmetic application. A polyurethane foam was prepared.

  At this time, the total supply amount of the liquid raw material was 0.6 kg / min, and the supply amount of nitrogen gas was 1.8 L / min (volume conversion at 0 ° C. and 1 atm). When the specific gravity of the liquid raw material is 1, (the supply amount of nitrogen gas) / (the total supply amount of the liquid raw material) is three times.

Example 2
Polyol in which propylene oxide is addition-polymerized to an initiator having two functional groups in the presence of an alkali catalyst, and ethylene oxide is further addition-polymerized so that the terminal hydroxyl group primary ratio is 80% and the number average molecular weight is 2,400. (Polyol B) was prepared.

  The raw material was prepared so that it might become the same composition as Table 1 except having used polyol B instead of polyol A. A polyurethane foam for cosmetic application was produced in the same manner as in Example 1.

Comparative Example 1
In the presence of an alkali catalyst, propylene oxide was addition-polymerized to an initiator having 3 functional groups to prepare a polyol (polyol C) having a terminal hydroxyl group primary conversion of about 2% and a number average molecular weight of 3000.

  The raw material was prepared so that it might become the same composition as Table 1 except having used polyol C instead of polyol A. A polyurethane foam for cosmetic application was produced in the same manner as in Example 1.

Comparative Example 2
In the presence of an alkali catalyst, propylene oxide was addition-polymerized to an initiator having 2 functional groups to prepare a polyol (polyol D) having a terminal hydroxyl group primary conversion of about 2% and a number average molecular weight of 2000. .

  The raw material was prepared so that it might become the same composition as Table 1 except having used polyol D instead of polyol A. A polyurethane foam for cosmetic application was produced in the same manner as in Example 1.

Comparative Example 3
In the presence of an alkali catalyst, propylene oxide is addition-polymerized to an initiator having 3 functional groups, and further ethylene oxide is addition-polymerized, so that the terminal hydroxyl group primary ratio is 73% and the number average molecular weight is 5000. (Polyol E) was prepared.

  The raw material was prepared so that it might become the same composition as Table 1 except having used polyol E instead of polyol A. A polyurethane foam for cosmetic application was produced in the same manner as in Example 1.

Comparative Example 4
In the presence of an alkali catalyst, propylene oxide is addition-polymerized to an initiator having 3 functional groups, and ethylene oxide is addition-polymerized, so that the terminal hydroxyl group primary ratio is 30% and the number average molecular weight is 3300 polyol. (Polyol F) was prepared.

  The raw material was prepared so that it might become the same composition as Table 1 except having used polyol F instead of polyol A. A polyurethane foam for cosmetic application was produced in the same manner as in Example 1.

Example 3
As a part of the polyol, a polymer polyol (polymer polyol A) obtained by graft polymerization of acrylonitrile on a polyether polyol having 3 functional groups and a number average molecular weight of 5000 was prepared. 40 parts by mass of polyol A (used in Example 1) and 60 parts by mass of polymer polyol A were mixed, the apparent number average molecular weight was 3560, the apparent average number of functional groups was 2.6, and the terminal hydroxyl group A mixture (polyol mixture A) having an average primary conversion rate of 55% was prepared.

  The raw material was prepared so that it might become the same composition as Table 1 except having used polyol mixture 1 instead of polyol A. A polyurethane foam for cosmetic application was produced in the same manner as in Example 1.

Comparative Example 5
20 parts by weight of polyol A and 80 parts by weight of polymer polyol A were mixed, the apparent number average molecular weight was 4280, the apparent average number of functional groups was 2.8, and the average primary terminal ratio of terminal hydroxyl groups was 42%. A mixture (polyol mixture B) was prepared.

  The raw material was prepared so that it might become the same mixing | blending as Table 1 except having used polyol mixture B instead of polyol A. A polyurethane foam for cosmetic application was produced in the same manner as in Example 1.

The polyurethane foam for cosmetic application produced in Examples 1 to 3 and Comparative Examples 1 to 5 were evaluated for foam moldability, apparent density, tensile strength, and average cell diameter. The results are shown in Table 2.

Table 2 shows the following.
When a polyol having a low average primary ratio of terminal hydroxyl groups is used as in Comparative Examples 4 and 5, the reaction is slow and cell coalescence tends to occur. The resulting polyurethane foam has a large cell diameter and a high density. Become. When a polyol having an average primary hydroxylation rate of terminal hydroxyl groups of 50% or more is used, the resulting polyurethane foam has a small cell diameter and can be reduced in density.

  Comparing the initiators used in the synthesis of the polyol with those having 2 functional groups and those having 3 functional groups, when the one having 2 functional groups is used, the resulting polyurethane foam has high tensile strength and is difficult to break. Comparing Examples 1 and 2 in which the number of functional groups of the initiator used in the synthesis of the polyol is 2, Example 1, which has a higher terminal hydroxyl group primary conversion rate of 92%, has a higher terminal hydroxyl group primary conversion rate. The average cell diameter of the polyurethane foam can be made smaller than in Example 2 which is 80%.

  When Example 3 and Comparative Example 5 using a polyol mixture are compared, the polyurethane foam obtained in Example 3 shows superior physical properties. That is, the polyol mixture of Example 3 contains 30% by mass or more of a polyol having a terminal hydroxyl group primary conversion ratio of 70% or more and a number average molecular weight of 1000 to 3000, and the terminal hydroxyl group has an average primary conversion ratio of 50% or more. Therefore, polyurethane foam has a small average cell diameter and low density.

Examples 4-8 and Comparative Examples 6-9
The effect of the amount of polyisocyanate (isocyanate index) or the amount of inert gas on the properties of polyurethane foam was investigated when producing a polyurethane foam for cosmetic application by mechanical foaming using a disk-type Oaks mixer.

Example 4
Polyol A was used as the polyol. A polyol, a crosslinking agent, water as a foaming agent, a foam stabilizer, an amine catalyst (urethane reaction catalyst), and a polyisocyanate were prepared so as to have the composition shown in Table 3. Example 4 is the same as Example 1 except that water is used as the foaming agent.

  A mixture of raw materials other than polyisocyanate is continuously supplied to Oaks mixer, nitrogen gas is supplied, discharged while reacting with polyisocyanate in Oaks mixer, and cured at 100 ° C for 7 minutes for cosmetic application. A polyurethane foam was prepared.

  At this time, the total supply amount of the liquid raw material was 0.6 kg / min, and the supply amount of nitrogen gas was 1.8 L / min (volume conversion at 0 ° C. and 1 atm). When the specific gravity of the liquid raw material is 1, (the supply amount of nitrogen gas) / (the total supply amount of the liquid raw material) is three times.

Example 5
A polyurethane foam for cosmetic application was produced in the same manner as in Example 4 except that the isocyanate index of the polyisocyanate was 90.

Example 6
A polyurethane foam for cosmetic application was produced in the same manner as in Example 4 except that the isocyanate index of the polyisocyanate was changed to 110.

Example 7
By making the total supply amount of the liquid raw material at the time of mechanical foaming 0.6 kg / min and the supply amount of nitrogen gas 1.4 L / min, (the supply amount of nitrogen gas) / (the total supply amount of liquid raw material) A polyurethane foam for cosmetic application was produced in the same manner as in Example 4 except that the ratio was 2.3 times.

Example 8
By making the total supply amount of the liquid raw material at the time of mechanical foaming 0.6 kg / min and the supply amount of nitrogen gas 5.4 L / min, (the supply amount of nitrogen gas) / (the total supply amount of the liquid raw material) A polyurethane foam for cosmetic application was produced in the same manner as in Example 4 except that the ratio was 9.0 times.

Comparative Example 6
A polyurethane foam for cosmetic application was produced in the same manner as in Example 4 except that the isocyanate index of the polyisocyanate was changed to 80.

Comparative Example 7
A polyurethane foam for cosmetic application was produced in the same manner as in Example 4 except that the isocyanate index of the polyisocyanate was set to 135.

Comparative Example 8
By making the total supply amount of the liquid raw material at the time of mechanical foaming 0.6 kg / min and the supply amount of nitrogen gas 1.0 L / min, (nitrogen gas supply amount) / (total supply amount of liquid raw material) A polyurethane foam for cosmetic application was produced in the same manner as in Example 4 except that the ratio was 1.7 times.

Comparative Example 9
By making the total supply amount of liquid raw materials at the time of mechanical foaming 0.6 kg / min and the supply amount of nitrogen gas 7.2 L / min, (supply amount of nitrogen gas) / (total supply amount of liquid raw material) A polyurethane foam for cosmetic application was produced in the same manner as in Example 4 except that the ratio was 12.0 times.

The apparent density, tensile strength, Asker F hardness, average cell diameter, ventilation resistance, appearance, and feeling of use were evaluated for the polyurethane foams for cosmetic application produced in Examples 4 to 8 and Comparative Examples 6 to 9. The results are shown in Table 4.

  Comparing the examples of Table 4 with Comparative Examples 6 and 7, it can be seen that if the isocyanate index of the polyisocyanate is in the range of 85 to 130, the physical properties, cell diameter, and feeling required for use as a sponge puff can be achieved.

  When the Examples in Table 4 and Comparative Examples 8 and 9 are compared, if (the supply amount of nitrogen gas) / (the total supply amount of liquid raw material) is in the range of 2 to 10 times, the physical properties necessary as a sponge puff, It can be seen that the cell diameter and the feeling of use can be achieved.

Examples 9-10 and Comparative Examples 10-12
The performance of the sponge puff for cosmetic application according to the present invention and the conventional sponge puff for cosmetic application were compared.

Example 9
The polyurethane foam produced in Example 4 was cut to a thickness of 8 mm, polished, and tested as a sponge puff for cosmetic application.

Example 10
After crushing the polyurethane foam produced in Example 4, it was cut into a thickness of 8 mm, polished, and tested as a sponge puff for cosmetic application.

Comparative Example 10
The test was performed using a sponge puff for makeup application made of a commercially available wet type polyurethane foam and having a thickness of 8 mm.

Comparative Example 11
The test was performed using a commercially available sponge puff for cosmetic application made of NBR latex foam.

Comparative Example 12
The test was conducted using a commercially available sponge puff having a thickness of 8 mm obtained by bonding a silicone foam having a thickness of 0.5 mm and an NBR latex foam having a thickness of 7.5 mm.

  FIG. 1 shows a photograph of the sponge puff for cosmetic application of Example 9 taken at a magnification of 100 with a scanning electron microscope. FIG. 2 shows a photograph of the sponge puff for cosmetic application of Example 10 taken at a magnification of 100 with a scanning electron microscope. FIG. 3 shows a photograph of the sponge puff for cosmetic application of Comparative Example 10 taken at a magnification of 100 with a scanning electron microscope. FIG. 4 shows a photograph of the sponge puff for cosmetic application of Comparative Example 11 taken with a scanning electron microscope at a magnification of 100 times.

  As shown in FIG. 3, a sponge puff for makeup application made of a commercially available wet polyurethane foam has a resin agglomerated cage-like structure and has a structure in which a large number of through holes are opened. When the liquid foundation is applied using such a sponge puff, the liquid foundation easily penetrates into the sponge, so that a larger amount of foundation than that actually applied to the skin must be used.

  As shown in FIG. 4, the sponge puff for makeup application made of a commercially available NBR latex foam has an open cell structure in which a large hole is opened in the cell membrane.

  The sponge puff for cosmetic application made of the polyurethane foam according to the present invention shown in FIG. 1 has a smaller size of the hole opened in the cell membrane than that in FIG. When such a sponge puff for cosmetic application is used, the amount of liquid foundation that can penetrate can be reduced as compared with Comparative Example 10 (wet polyurethane foam) and Comparative Example 11 (NBR latex foam).

  The sponge puff for makeup application made of polyurethane foam according to the present invention shown in FIG. 2 is crushed after foaming, so the size of the hole opened in the cell membrane is slightly larger than that in FIG. Small compared to 4. Even when such a sponge puff for cosmetic application is used, the amount of the liquid foundation that can penetrate can be reduced as compared with Comparative Example 10 (wet polyurethane foam) and Comparative Example 11 (NBR latex foam).

  Next, for the sponge puffs for cosmetic application in Examples 9 to 10 and Comparative Examples 10 to 12, in addition to the evaluation of apparent density, Asker F hardness, tensile strength, ventilation resistance and feeling of use, the same as in Table 4, Abrasion, liquid cosmetic residual ratio, liquid cosmetic penetration depth and caking resistance were evaluated. The results are shown in Table 5.

  The abrasion resistance was evaluated according to the following test method 1, the liquid cosmetic remaining rate and the liquid cosmetic penetration depth were evaluated according to the following test method 2, and the caking resistance was evaluated according to the following test method 3.

Test method 1
Using the skin surface of the polyurethane foam produced in Example 4, and applying the powdery foundation to the skin surface with the sponge puff for cosmetic application of Examples 9 to 10 and Comparative Examples 10 to 11 was performed 1000 times. Then, the damaged state of the sponge puff after carrying out this test was examined.

Test method 2
About 0.2 g of liquid foundation was dropped onto the sponge puff for cosmetic application of Examples 9 to 10 and Comparative Examples 10 to 11. The liquid foundation adhered to the sponge puff for cosmetic application was rubbed 50 times on the skin surface of the polyurethane foam in the same manner as in Test Method 1. The liquid cosmetic residual rate R (%) was determined by the following equation, where M ₀ was the mass of the liquid foundation dropped and M ₁ was the mass of the liquid foundation remaining in the sponge puff after the test.

R (%) = (M ₁ / M ₀ ) × 100
After this test, the sponge puff for makeup application into which the liquid foundation has penetrated is cut in the vertical direction, the position where the liquid foundation has penetrated is confirmed by the color change observed visually, and a ruler is pressed against the cross section. The penetration depth (mm) from the surface was measured.

Test method 3
The cosmetic sponge puffs of Examples 9 to 10 and Comparative Examples 10 to 12 were each applied with 10 g of powdery foundation and applied to the skin until the powdery foundation disappeared to examine whether or not the caking phenomenon occurred. .

  When the cosmetic sponge puffs of Examples 9 to 10 were used for applying the liquid foundation, the amount of the liquid foundation (residual rate and penetration depth) that remained inside the sponge puff and could not be used was compared with Comparative Example 10. It was confirmed that it can be reduced more than -11 cosmetic sponge puffs. Even when the cosmetic sponge puffs of Examples 9 to 10 were used for application of powdery foundation, they could be used to the end without caking. Regarding the feeling of use, the cosmetic sponge puff of Comparative Example 11 felt somewhat rough, but the cosmetic sponge puffs of Examples 9 to 10, Comparative Example 10 and Comparative Example 12 had a pleasant texture that was difficult to feel rough.

Claims (4)

A process for producing a polyurethane foam by mechanical foaming using a polyol, a polyisocyanate, a catalyst, a foam stabilizer and an inert gas,
The polyol contains 30% by mass or more of a bifunctional polyol having a terminal hydroxyl group primary conversion ratio of 70% or more and a number average molecular weight of 1000 to 3000, and an average primary conversion ratio of terminal hydroxyl groups of all polyols is 50%. Use what is above,
The polyisocyanate is used in the range of an isocyanate index of 85 to 130,
In volume conversion at 0 ° C. and 1 atm, the supply amount of the inert gas is 2 to 10 times the total supply amount of the liquid raw material containing the polyol, polyisocyanate, catalyst and foam stabilizer. A method for producing a polyurethane foam for cosmetic application.   Addition polymerization of propylene oxide to the initiator in the presence of an acidic catalyst to prepare a bifunctional polypropylene glycol having a terminal hydroxyl group primary conversion rate of 40% or more, and further addition of ethylene oxide to the terminal hydroxyl group primary A bifunctional polyol having a conversion rate of 70% or more and a number average molecular weight of 1000 to 3000 is prepared, containing 30% by mass or more of the bifunctional polyol, and an average primary conversion rate of terminal hydroxyl groups of all polyols is 50% or more. A method for producing a polyurethane foam for cosmetic application according to claim 1, wherein a polyol is prepared.   The method for producing a polyurethane foam for cosmetic application according to claim 1 or 2, wherein less than 1.0 part by mass of water is used as a foaming agent with respect to 100 parts by mass of the polyol.   4. The method for producing a polyurethane foam for cosmetic application according to claim 1, wherein the foamed polyurethane foam is crushed.

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